Designing Castles

[Kevlar]

Considering the sort of world I have created, and my... thorough approach to worldbuilding, I'll be needing to design tons of castles. While sometimes I do have issue deciding where curtain walls and towers and the like should go, I have a few things I do that makes this easier. My biggest issue is castle buildings. Especially the keeps. I don't know how many rooms it should have besides the basics like a hall, kitchen, library, solar and so on. How many rooms for the garrison, when there is one?

A bigger issue is the actual layout. Lighting being the biggest. I can't seem to figure out how to get a window or two in every room. Doing so always gives thin, long, buildings, or ones with awkward shapes and so on.

Anyone have any resources on this? Internet is most convenient, but it doesn't have to be. My Googling has elicited only tutorials on modelling basic castles in 3D. Not what I was looking for.

Or how about just tips or gathered knowledge.

Thanks in advance.

 

[Chilari]

I suggest you take a look at the layouts of real medieval castles and how they changed over time. Kenilworth castle is a good one, as is Ludlow. A classmate of mine did his dissertation on castle gateways, and concluded that they were more for show than defence, particularly in the later medieval period, though his focus was really on northwest England. The book Medieval Castles by Oliver Creighton might be a good one to use - I am informed that he knows what he's talking about when it comes to castles, but then my informant may be biased in his favour since they taught him as masters and PhD level. What can I say? My university is one of the best for archaeology.

 

[Ravana]

Second that... there are plenty available on line (as well as no few photographs of still-existing ones). One of the first things you'll discover, as I've mentioned elsewhere, is that interior hallways are almost exclusively an artifact of RPGs: in every case I can think of offhand, rooms either connected to a single hallway that went along a building wall (usually a courtyard wall, not a defensive one), or, more often, simply connected directly to one another. Reason? Lighting--you wanted windows in every space. (Second reason: halls were wasted space that could be put to better uses... which is another of the first things you'll discover: most castles weren't actually all that big.)

Don't have time to respond more fully tonight, I'm afraid. I'll see what references I still have available (most, unfortunately, were on the computer that died, and were not backed up... since I can always locate them again, if I feel the need to), and get back here again tomorrow.

 

[Kevlar]

I'll take a look at Kenilworth and Ludlow, if I can find detailed floorplans. You've also given me another reference book to watch for.

I realized quite a while ago that interior hallways and rooms were a bad idea. I was designing a giant castle/palace when I took a good look and thought, "Damn that place would be dark." I still do have one interior corridor in my story, but its in a two-storey keep of a largely insignificant lord and I justify it by saying there's a glass roof, or rather, glass panels in the roof. Nothing you'd be able to see through, just crude, greenish glass.

As far as size, this might be my biggest issue. I can never solve this issue. I always make the castle either too big, where I start to wonder what they'sd do with all the extra rooms, or too small, where all the garrison will be cramped into 4x6 (metre) or similiar room.

I suppose I could fit more rooms in if I took out the corridors altogether, but does this work for living quarters? Not the noble family's room, surely, but rooms for guests and the garrison? Also, is there precedent for having 'landlocked' (can't think of the word I'm actually looking for) rooms without windows on the walls but with sunroofs?

I really do appreciate castles, but unfortunately I've never been in one. If and when I go on an international vacation I don't want Mexico or Cuba. Give me somewhere with castles and thousands of years of history. Sometimes I envy Europeans their proximity for these amazing structures. My distance from them causes my designs to be clogged by artifacts of video games, movies, and inaccurate literature.

 

[Chilari]

Generally, if you need more rooms, up is the direction to go. A large tower might have levels divided into two rooms, with a small landing room off the stairs with doors to each.

Oh and Chateau du Suscino in Brittany, France is a good castle too. It's near where my grandparents live so I've been there a fair few times. It's been largely reconstructed in the last couple of decades so now it looks really awesome, with pointy rooves and stuff; when i first went there is was little more than a ruin. I have some photos too, if you're struggling to find some on the net. Oh and I might be able to help with Kenilworth and Ludlow castle plans; I'll check when I get back home later.

 

[Map the Dragon]

There is an intricate D&D Castle Guide that provide a plethora of hints, tips, and information for those approaching the topic of castles from the design perspective for gaming or for story. I bought it years and years ago and reference once in a while to answer a question or get a picture in my mind of what I'm doing in story telling. You might want to check this out as a possible resource.

 

[ShortHair]

Keep in mind that privacy and individual rooms are recent changes in culture. People in medieval times shared space because, often, their house only had one room. A castle is bigger but not necessarily better.

 

[Donny Bruso]

Pretty much second what everyone else has said, except for the castle visits, I haven't had that privilege yet. Considering all the things that a self-sufficient castle would need to have inside the walls to withstand a lengthy siege, and those it would have there simply for convenience, it's almost hard to go too big. There's always something else to stuff inside.

As far as your garrison being all in one room, that's probably the most realistic way to go. Even today a large number of military bases use 'open bay' type rooms for barracks. 4x6 meters might be a bit small for your entire garrison, but again this depends on the size of the overall castle. Obviously larger castle means larger garrison.

Curtain walls and towers, well in the most basic sense the curtain wall just surrounds the keep and out-buildings. Aside from terrain features to take into consideration there isn't too much to deciding where to put it. You probably want to decide how it's constructed first though, so you know how thick it's going to be and how much space the wall itself will be taking up. It's not as simple as a bunch of stones stacked on top of each other, methods of wall construction changed several times in the middle ages to keep pace with siege technology. Towers, well any time your walls meet at an angle, there would be a tower there for reinforcement. Makes the wall stronger and harder to breach. However if you have long runs of straight wall, there should be some in there as well, both for strength and defensibility.

Lighting is pretty much as others have said. Hallways are going to be rare. Remember that unless you decide to create a light source other than fire in it's many forms, you're pretty much dependent on every last iota of natural light you can squeeze into the castle, because torches, candles, etc. all cost money. Rich people don't get rich by wasting money. Skylighting is certainly an option, but remember that it has drawbacks. From a defensive standpoint, it's a lot easier to throw something through a glass ceiling than a wooden or stone one. Also, glazing technology is probably not where it is today, so your skylights are, in a realistic world, likely to leak, dripping into your candles, torches, drinks, the Lady's hair, etc.

Remember overall you want to look at the cost of construction. Huge castles are great, but they are expensive. Bigger curtain wall to fit in more stuff means more towers, more stone, more timber, more peasants whining about being repressed... Just like now, it really comes down to money. How rich is your Lord, and how much is he willing to spend on his home?

 

[Kevlar]

Thanks for all the info so far. Also, does anyone have some good info on the size of (great) halls in different castles? I'm trying to decide how large to make the keep of a castle I'm working on. The castle isn't huge, but it does have quite a few towers and bastions. I'm attaching a quick plan to give a sense of scale, though the scale is far from set in stone. This castle is set on a river island, if anyone wants to know. The portion at the bottom is where the gates are. At the top is the garden, veggie and flower both. I've also sort of scrapped the idea of the turrets on the keep.

Now: My idea is that as soon as you enter the keep you are under a small, vaulted area. To the left you would enter the hall, with the dais at the back end. From the dais there is a stairway going up, to the right, and if you turn right in it there is a secret passage along the length of the dividing wall that goes down, circles around, and down into a hidden cave with boats ready to escape into the river. Below the dais, there is a doorway going through the dividing wall, under the secret passage, and into the kitchen. The kitchen has some stairs leading down to cellar and larder, and a door exiting the back of the keep into the garden. Along the rest of this side of the main floor there would be some other important rooms. While the hall goes up three storeys, the right side of the keep uses those three storeys as three storeys. But that's not important.

My question is, what would be an appropriate size for the keep, considering the hall takes the left half? This will become an important location to my story, and the seat of a king. And please, no 'You don't need the size, just allude at it' comments. I like designing castles. My biggest problem is scale. Would something like 150' sound appropriate? Too large? In the drawing its eighty, but that makes it far too narrow when split in half, and not so long as it is.

Also, what would be a good thickness for the walls of tower, keep and curtain wall? It is up on high on the island, and the only truly vulnerable spot is the gate, but siege machines have a way of making the invulnerable vulnerable.

I also think I'm going to make the courtyard bigger and put the keep in the middle of it. Anyone have a reason this would be worse?

 

[Ravana]

What you have is immense. Though, to explain why, my reply will end up being similarly immense (oh, like that's different )--so I'm going to post it in sections as I finish it. I'll let you know when I'm running down, so you can start asking any new questions that occur to you.

 

[Ravana]

Okay, first rule of design: "form follows function."

Except for castles, that's the second rule of design. The first rule is "form follows terrain."

Unless you are thinking this has been built on flatland, there is almost zero chance it would be configured the way you have it now. Though here you run into the second rule as well: is this a "castle," or is this a "palace"? The same building can serve as both, of course, and often did... but a castle is something you build with defense foremost in mind, whereas a palace is something that you may want to make defensible. If it's the second of these, it's probably going to be made defensible more by being enclosed within city walls--and a few dozen, or hundred, leagues of home territory--than by having 20' thick curtain walls of its own. What follows assumes that this was, at least originally, built for the "castle" function.

Whenever possible, defensive fortifications are going to take maximum advantage of terrain. In most cases, this means high ground, and not gently sloping high ground, either. Unless you're in mesa territory, the crowns of steep-sided rocky protuberances tend to be limited in size. Doesn't mean your king didn't luck out on a big one in your world, but it's definitely not common for real-world Europe.

The second most common option is similar to what you went with: put it someplace where access is limited by water. Usually, that's in the bend of a river, not an island in one, for various geophysical reasons involving how wide rivers are, how islands are formed in them, what those islands consist of when they do form, and how long they remain islands before one channel silts up and they become peninsulas anyway. Or, to put it another way, you can't build thick-walled stone constructions on a mudbar... whereas if the site were a stone outcropping, the river would almost invariably have gone around one side of it, not both, and even if its channel eventually shifted (which they do), it would have ended up going around the other side of it, not both. Again, there are exceptions (Ile de la Cite in Paris, Manhattan)--but they're rare, and most are probably larger than you want, rather than smaller. And few offer significant elevation, whereas stone outcroppings that a river goes around can provide the best of both worlds.

Anyway: assuming terrain is an issue, you would not see the sprawling architecture you currently have. (It's not likely you'd see it regardless, but we'll get to that in the next section.) The good news, for your putative defenders, is that if the castle does take up all or nearly all the usable land, however it is sited, then most siege equipment won't be much of a worry: stone throwers have very limited ranges, mining won't be possible, and towers would be difficult to advance to a wall.

That's terrain, in brief. On to construction....

 

[Ravana]

How it's put together: defensibility.

In order to have maximum defensibility, you want the minimum of wall surface--which is why castles generally followed a ring-like configuration (subject to what the terrain allows). Which means those projecting towers you have are no-nos, unless they're each completely surrounded by steep dropoffs and that's the only thing that would fit there. In fact, not all castles will have anything projecting beyond the curtain walls: while it's great to be able to provide flanking fire against anyone trying to assault one, it's also that much more exposed surface area. Plus, it's a waste of space, again barring that being the only thing that could fit there, since it implies that you have actually "recessed" your curtain walls in order to achieve that flanking fire. Far more common is to see something projecting out from the top of the curtain wall itself--permanent stone construction or temporary wooden ones--allowing things to be dropped directly on people all along the wall.

Layered defenses are good--an outer ward with what are likely the most heavily-fortified buildings, such as barbicans (a gatehouse enclosing a passage about wagon-width, often housing more than a single interposable barrier, often with murder holes to make life even more miserable for the attackers trying to batter their way through one obstacle after another), followed by one or more inner courtyards. If this is the configuration you want, your "main" keep will be in the innermost such layer, not linking two of them together. In fact, the various "rings" of defense may not be directly interconnected at all: each may effectively be a separate "castle," with space (moats, wet or dry) between them.

Next, consider what the defenders themselves need. Number one here is the ability to react to events taking place anywhere along their current defensive perimeter... in other words, soldiers are useless unless they can get to where they're needed. The faster they can do that, the fewer are needed. Again, this means greater centralization, fewer projecting areas, less total surface area to defend, and above all easy lines of internal communication. If you expect your outer layers to be breached with regularity, you can arrange for these lines to be easily cut, by more than just heavy doors: portcullises, drawbridges--even along parts of the curtain wall: a six-foot gap with a ten-foot drop below it will slow most attackers way down--and so forth. The trick is to balance internal communication with obstruction when layered defenses are involved: you may end up cutting off some of your troops when you act to isolate an inner area. Which isn't always a totally bad thing, if they have areas they can fall back to and reasonably defend on their own (towers, usually), at least long enough for a counterattack to be organized to attempt their relief.

Next step: interiors.

 

[Kevlar]

I guess you'd have to see the terrain I came up with in order to understand. It's not all level. The gate area is the lowest, the offest towers are the next two lowest parts and then what is now the garden. The only flat part is the upper bailey. Most all of it is situated on a rocky outcrop, but there is gentler slopes on the rise. Does it make it more believeable that the whole forst it's in was once a delta? The deposits and volcanic activity of the area turned it into a rough land, with well carved divergences in the rivers. Is this likely to actually happen though?

I'll shut up now until you've finished saying what you're saying, and then all these issues can be fully addressed.

Also: Those jutting towers aren't for flanking fire, they're to protect the bridges that lead to the island.

 

[Ravana]

How big on the inside?

There are two main elements to consider here, one of which is absolutely critical. Lighting... is the other one.

Because lighting won't do you any good if your roof falls in.

The size of interior rooms is limited, first and foremost, by how much roof you can support. If you're building stone pillars throughout the space, this can be effectively unlimited. If you aren't--then your supporting walls will rarely be more than thirty feet apart. (That's nine meters, to you. ) (Yes, I know: you did give it in feet on your drawing.)

Thirty. Feet. Why? Because of what supports your roof... which is wood. Yes, you can build stone arches--guess what? They won't even be that far apart, most cases. And they'll probably still be supporting a largely wooden roof. Care to guess why there are so many ruined castles around, with the exterior walls surviving and nothing else? Because that's all that was made of stone in the first place. All the interior structure--roof, ceiling/floor, most interior walls--will be wood. So the maximum width of a room will be dictated by how much you can span with a single wooden beam. Yes, trees grow taller than thirty feet, but consider: you need thirty feet of perfectly straight beam of a uniform thickness--a fairly substantial thickness, if there's anything above it other than cross-framing for a peaked roof (like, say, additional levels), and no small thickness even if there isn't. And you need that for each beam... and it's gonna take more than one. Probably one every three or four feet, if they're supporting additional levels; they can be spaced a bit farther apart if it's only for the roof.

Though this is obvious if you think about it, it isn't necessarily if you never have: your crossbeams will only run across the short direction of the room. Running them across the long one is a waste... as is running them both directions, since you'd end up laying one direction across the other, which would only double the weight of the supporting beams without adding meaningfully to the strength of the structure. Which is why you can't get away with saying you don't need 30' beams for a 30' wide room, because its other dimension is only, say, 20': of course you don't. That isn't a 30' wide room, that's a 20' wide room that's 30' long.

So what is the maximum length of a room? Well... how big around is the planet? Frivolous answer (and deceptive, since building on a curved surface is a pain...), but essentially accurate: doesn't make the slightest difference--there is no limit. Which is why cathedrals aren't built on circular plans: they'd have to downsize if they were. (For an interesting and easily-accessed example, look up San Vitale in Ravenna, Italy--actually octagonal, but the same principles apply.)

Oh, wait: cathedrals do tend to have large interior spaces, don't they? This is true. And it's astounding how many of them are slightly less than 100' wide, total... and those are the ones built almost entirely of stone, and even then the roof is supported by rows of columns. Many of these aren't divided exactly evenly by the rows of columns: the center of the nave might be a whole 40' wide. Very few are wider. And by "very few," I mean that Notre Dame is not. Neither is Salisbury. St. Peter's Basilica is; it was also designed by three of the greatest architects in the history of Western Europe, was built near the end of the Renaissance, on an essentially unlimited budget, and was the first building in a thousand years to surpass the Hagia Sophia, which was built during the height of the Byzantine Empire on an essentially unlimited budget and using an architectural plan so innovative and unique that it has never been fully duplicated. (My admiration and astonishment for that building aside, there are actually some good reasons not to follow the plan. But ya know what? It's still standing. And it's still huge... and gives the impression of even more open interior space than St. Peter's does.)

And considering what they needed to give up to get even that measly 40', let alone the larger widths, you aren't going to see that in fortifications, or even palatial residences. For starters, there's no "second storey"--not down the middle, at least. After the early Gothic period, most of them didn't have one down the sides, either. They also don't have walls. Which may sound silly to say, but take a good look at the ground plans: they're actually rows of pillars connected mainly by windows. For two reasons: first, they dug the windows. Second, the more windows you have, the less your walls weigh, therefore the less the building weighs overall, therefore the less you need to support. And even then, they eventually had to add another row of pillars on the outside of the building to achieve the effects they wanted--though these got called "flying buttresses" instead. The ground-level footprint of a High Gothic cathedral such as Notre Dame could be as much as three times the usable interior space: find a picture of Notre Dame's apse end. (Couldn't resist the pun. Didn't make up the term, though. By the way, the best achievement of the "no-walls" effect was actually constructed fairly early in the Gothic period: Sainte-Chapelle. If you've never seen an interior picture, find one: you'd swear it really doesn't have walls. Makes most Gothic cathedrals look like prison cells by comparison. Then find an exterior picture, if you want to ruin the illusion... or just be impressed and skip that step.)

Note that all the above is discussing the maximum distance between load-bearing elements. A building could be 50' wide if it was divided evenly down the middle by a wall--could be infinitely wide, as long as you kept putting structural walls in. Or pillars... and wooden ones work just as well as stone, as long as they're supporting wooden construction above. Just remember that each time you add another level--roof included--you increase the load on everything below it. Which is one reason most roofs are peaked, often steeply so: you can't afford to add the weight of a bunch of snow or ice to it. And the roof will most likely weigh more than any single storey: not only does it require the framework (which, extending vertically as well as horizontally, weighs that much more... and the steeper the slope, the more it weighs), but whatever you're covering it with will weigh at least as much as wood; more, if you're looking at slate, tile, lead or copper.

Okay, that's the structural part of the interior. One more section....

 

[Ravana]

Interior decorating:

Now for the other reason Gothic cathedrals are designed the way they are: light. Not only do they allow greater amounts of the wall to be cut away and replaced with glass, the height of the room allows that much more window area for the same floor space.

Your castle does not have this option. People expecting to have stones thrown at them can't afford to live in glass houses.

However: in all likelihood, your "great hall," whatever its other dimensions may be, will also be more than one storey high. For both structural and lighting reasons: you get the increased windows, and you eliminate a floor's worth of weight, so the room can be wider. Probably, your great hall will not have anything above it other than the roof. Even then, odds are the central space will not be more than 30-ish feet wide... though by judicious use of columns, you can tack on extra width along the side. The seating may be a bit "obstructed view," but if you have that many people to pack into one space, they can't all be important enough to have clear line of sight anyway, right?

Everywhere else in your castle... well, the rooms aren't going to be 30' wide. Who needs that much space, anyway? Especially if you can make it long. But there's the other reason, too: someone sitting along the far side of that room, away from the windows, isn't going to be able to see well enough to do anything useful anyway. Don't believe me? Walk through your house when the lights are off. Tell me how far away from a window you can get and still be able to read. For that matter, tell me how far away you can get from a window, period. And then consider that your windows are probably wider than those your castle-dwellers have available to them... especially if their rooms are along exterior (i.e. defensive) walls.

You will discover that, in most castle construction, rooms were generally no more than about 15' wide. Which means the entire building can only be 30' wide, and then only if it has windows on both sides. Which it often won't--for reasons that go back to both structural integrity and not wasting space.

A lot of the living space of your castle will connect directly to the exterior walls. Quite possibly, all of it will. Why waste perfectly good walls you've already built--and which are stronger than anything you're going to put up on the inside? Especially since you're going to need to allow space between those walls and buildings inside of them anyway if you want light to be able to reach? (For similar reasons, nearly all the major buildings will connect with each other: that's one less wall you have to build.)

This doesn't mean that all your buildings are limited to 15' wide. A considerable amount of the interior space doesn't need to be well-lit: bedrooms, for instance, can get by just fine without windows, as long as you don't do much in them other than sleep. You might not even get dressed in them, if each apartment also has a parlor; this allows for longer, narrower apartments, and thus more housing. Storerooms don't need light often enough to worry about it: you take your own in when you need to, and the rest of the time they're pitch black. Workrooms might face southeast, so that they get direct light in the morning and much of the afternoon; when it gets later than that, activity moves to other parts of the building. And so on.

I can pretty much guarantee, however, that your 100'-square keep is out of the question. Not unless it has a light well down the center (essentially a mini-courtyard, designed to allow light and air in, and nothing else).

Oh, right: air. HVAC in general, in fact. Air needs to be able to circulate through the areas that see constant use; these areas also need to be heated (and, ideally, have a good way to cool during summer); and the smoke from what artificial light you do use, plus that of the heating and cooking fires, needs to get out. All of which is easier with smaller spaces than large ones--heating especially. I'll let you worry about those details on your own for now, apart from the small impact they have on floor plans... if lighting, structural integrity and space considerations can be overcome, those others aren't going to swing things the other way anyway.

You'd probably be astonished at how few rooms most castles actually had--at how small they were in general. As mentioned by others, individual rooms were not exactly the rule: in many cases, the lord of the castle had one, and no one else did. Of course, in many cases, no more than a couple dozen people lived there anyway; in some cases, a keep might not be inhabited at all day to day, even by its owner, but rather only when security was needed. Even the ones that were maintained by a standing garrison (expensive, since these people are non-producers) wouldn't have required a lot of people: as long as the walls were intact, and the doors couldn't be broken, a keep could be held by as few as a dozen men, perhaps less--at least long enough for someone to notice it was being threatened and round up the balance of his troops to relieve it. This doesn't apply to your situation directly, but it may cause you to adjust the number of men-at-arms you'd planned to house there... which, again, are expensive and largely useless individuals whenever there isn't a war on.

***

Finally--and probably the part you'd been most hoping for--a couple of castles for which floor plans (in many cases, photos) are easily available on the internet. I'll just name them, rather than providing links, and let you dig up as many views as you like. You can find a wealth of others just by Googling "castle floor plan image," too: these just happen to be some of the better ones, particularly for large-scale castles such as you have in mind. They also represent a good spread of time periods.

Krak des Chevaliers (Crusader castle in Syria, 11th century--and compared to most others, it's freakin' huge)

Windsor Castle (England, c. 12th century onward; while clearly quite defensible, it would probably fall closer to the "palace" classification)

Caernarvon (or Caernarfon) Castle (Wales, 12th-14th centuries--a definite contrast with Windsor: not a "palace")

Marienburg (or Malbork) Castle (now in Poland, the headquarters of the Teutonic Knights, completed 1406: particularly notable in that it is constructed of brick, not stone)

Stirling Castle (Scotland, present configuration 15th to 17th centuries)

Neuschwanstein Castle (Bavaria; actually 19th century, what happens when a noble has too much money and nothing better to do with it... you almost certainly have seen it before--especially if you've been to Disneyland, since it was the model for Sleeping Beauty's castle; again, as much "palace" as castle)

Also, if you want to go beyond "castle," you can look up the name Vauban... who, in the 17th century, as a consequence of the widespread use of gunpowder, completely redefined what large-scale defenses looked like. And did it so well that much of what he was responsible for still exists--not only because it was that strong, but because it's that hard to remove. But as I said, those aren't "castles" per se. They're just really cool.

 

[Ravana]

I guess you'd have to see the terrain I came up with in order to understand. It's not all level. The gate area is the lowest, the offest towers are the next two lowest parts and then what is now the garden. The only flat part is the upper bailey. Most all of it is situated on a rocky outcrop, but there is gentler slopes on the rise. Does it make it more believeable that the whole forst it's in was once a delta? The deposits and volcanic activity of the area turned it into a rough land, with well carved divergences in the rivers. Is this likely to actually happen though?

Basically, no, it would make it less believable: you don't get deltas around rocks. They occur when very large rivers hit very flat pieces of land... such as the ones at sea level right before you get to the sea itself. (Consider how few deltas of any size there are in the world. I can only think of nine I'm sure of off the top of my head... ten, if you count the Netherlands as one, though considering how much it's been redesigned, I don't know if it still qualifies at this point. I'm sure there are a couple more, but not many.) Doesn't mean there couldn't be a big rock somewhere in the middle of where it formed, only that it doesn't aid in believability. And I guarantee that the big rock would be the only meaningful elevation in such a situation... anything that wasn't projecting to begin with would be dead flat. At any rate, I still can't see much motivation for having towers out on "wings," rather than as part of an enclosing wall; unless the locations were so good that artillery from them could dominate the river branches, I would've been inclined to build the castle without them. (And in that case, I'd have built more there, unless that's all that would fit.)

I'd say you'd be better off setting it in (what was at least originally) a moderately steep river valley--where the water could be forced to part around the rock outcropping, without having the option of seeking a course of lesser resistance. The upriver face of the island would likely be sheer cliff (since it would have been eroding from whenever the river first reached it); the downriver section could trail off more gently. By the time the valley widened enough to no longer qualify as "steep," the channels on either side of the rock would both be well enough carved that they could both continue to be viable. This is the case with Manhattan; I believe it's also true of Paris, as well as the occasional locale along the Rhine and Danube, though don't quote me on that. Though note that if there's any reason for the river to prefer one direction to the other, even an inch or so (at first) of something that resists erosion better than the other channel does, eventually one branch will fade away, as the other gets cut deeper.

 

[Chilari]

To add to what Ravanna said about river islands: One thing about rivers is that, occasionally, they flood and burst their banks. Bridgnorth in Shropshire, UK is a town which not only has an island in the river, but also the remains of a medieval castle. The island, dispite being about 4 metres above the normal river level, ends up underwater about one year in three when the river floods. The castle, meanwhile, perches of a high hill that actually has cliffs facing the river. Of the three main medieval routes into the centre of the town on the hill, which was once walled, there are two very steep routes and one, to the northwest, which is more gentle. The steep routes went from the town to the quayside, since Bridgnorth used to be a key trading point - it was as far upriver as the river trading boats could go, thanks to the bridge for which Bridgnorth was named (the bridge that marks the northernmost point on the Severn a boat can go). There's no castle there now, or rather, there's a bit of the keep leaning over at an angle, but it makes a good case study when looking at the way a castle town was influenced by topography.

I'll read through Ravana's other massive replies later, when I have a few hours available. I'm meant to be working on my dissertation right now.

Note: Bridgnorth does not have an E in it. The one with an E in it is in Canada, and does not have a castle. Various national companies with shops in Bridgnorth don't know how to spell Bridgnorth, though, so my bank statements occasionally think I've been in Canada

 

[Ravana]

I'll read through Ravana's other massive replies later, when I have a few hours available. I'm meant to be working on my dissertation right now.

Hee hee. And I'm meant to be sleeping--which is what I intend to do starting really soon now. But I wanted to ask you about your dissertation, before I forgot (again)... so please be sure to remind me if I don't. (It can be in PM, if you think no one else will be interested. I assure you that I am.)

 

[SeverinR]

One sight I found helpful was "Parts of a castle"
Parts of a Castle
It is a good one stop information about castles.

"If you would be so kind to point me to the buttery, and send the butler with a glass and I shall not trouble you any more."
(Butler is the gentleman that takes care of the buttery.)

 

[SeverinR]

Just a side note on the subject:
If you have lots of money and don't have anything to do with it,
you can have a castle built by this company.
They don't build drafty castles either, they use insulation between the rock walls.

They also have castle plans so it might apply to this thread too. (I can't see the pictures at work though)
CASTLEMAGIC Castle builders

I would say look to period castles for technology of that time.
This sight has large rooms.

There is a castle at a ski resort for sell, 3 bed, 4 bath 4800 sq feet, just 2mill.